In order to check the functionality of system components, for example actuators, in complex systems, so-called intrusive tests are frequently conducted. These intrusive tests are often regularly carried out when certain predefined enabling conditions for conducting these tests are met. During operation of the system, when the enabling conditions are present an actuator is activated or adjusted, and one or multiple sensor variables is/are observed. If the expected response to activation of the actuator does not occur, a defect in the actuator or some other system component may be deduced.
In particular in engine systems of motor vehicles, these function tests are carried out within the scope of an onboard diagnosis for a majority of the actuators used therein. For example, in a coasting mode in which no fuel is injected into the internal combustion engine, a function check of the actuator for adjusting the swirl flap may be carried out. In this check, the position of the swirl flap in an air supply system of the internal combustion engine is varied, and the resulting change in pressure in the intake manifold of the air supply system or the change in the fresh air mass flow is measured. If there is no change in pressure, or if the expected change in pressure as the result of adjusting the swirl flap does not occur, a defect in the swirl flap may be deduced.
To allow a robust diagnosis, it is necessary for a predefined system state to be maintained for a given function test. The predefined system state may be defined by state variable ranges for state variables, it being possible for an enabling condition to include, for example, that a state variable must be within a state variable range or remain constant while the function test is carried out, since a change in the state variable would distort the test result. In the previous function checks of system components, during the course of the function test it is observed whether the necessary enabling conditions are met, and if applicable, the function test is terminated and the result is discarded. Depending on the selection of the state variable ranges, this may possibly result in frequent terminations of test runs, which is disadvantageous due to the fact that a function test has a negative influence, i.e., represents a disturbance. Frequently terminated test runs thus result in a high degree of negative influence on the overall system.
Correspondingly, the state variable ranges defined by the enabling condition should be selected to be relatively large so that there is a sufficiently high probability that the function test may, with a certain likelihood, be carried out to the end in the operated system. However, this may result in the function tests also having to be carried out in operating ranges in which the activation of the actuator to be tested, in order to check its function, causes a greater effect on the system.
Similar difficulties exist for balancing or calibrating of a system component which likewise is to be carried out regularly and/or under certain operating conditions. A property of a system component, for example a sensor variable of a sensor, is ascertained in a certain operating range, and an interpretation of the corresponding sensor variable is adapted in a control unit. Similarly, a physical output variable of an actuator may be ascertained regularly and/or under certain operating conditions as a function of a control of the actuator in order to appropriately adapt the output of the control variable by a control unit. In these cases as well, the balancing or the calibration must be terminated if the state variable range defined by the enabling condition is departed from prematurely, i.e., during ascertainment of the sensor variable or the physical output variable.
An object of the present invention is to provide a method and a device for carrying out a function check and/or a balancing or a calibration of a system component in a system, on the one hand the robustness of the function check or of the balancing being increased, and/or on the other hand the negative influences on the system being kept as low as possible during the adjustment of the actuator.